/*
 * The MIT License
 * 
 * Copyright (c) 2011 Takahiro Hashimoto
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package com.taobao.top.link.embedded.websocket.handler;

import java.nio.ByteBuffer;
import java.util.Random;

import com.taobao.top.link.embedded.websocket.WebSocket;
import com.taobao.top.link.embedded.websocket.exception.WebSocketException;
import com.taobao.top.link.embedded.websocket.frame.Frame;
import com.taobao.top.link.embedded.websocket.impl.WebSocketImpl;

/**
 * The Class MaskFrameStreamHandler.
 *
 * @author Takahiro Hashimoto
 */
public class MaskFrameStreamHandler extends StreamHandlerAdapter {
  /** The random. */
  private static Random random = new Random();

  /*
   * (non-Javadoc)
   * 
   * @see jp.a840.websocket.handler.StreamHandlerAdapter#nextUpstreamHandler(jp.
   * a840.websocket.WebSocket, java.nio.ByteBuffer,
   * jp.a840.websocket.frame.Frame,
   * jp.a840.websocket.handler.StreamHandlerChain)
   */
  @Override
  public void nextUpstreamHandler(WebSocket ws, ByteBuffer buffer, Frame frame, StreamHandlerChain chain) throws WebSocketException {
    // just for rfc6455
    if (ws instanceof WebSocketImpl) {
      chain.nextUpstreamHandler(ws, buffer, frame);
      return;
    }
    // mask-key + header + contents
    ByteBuffer buf = ByteBuffer.allocate(4 + buffer.remaining());
    int limit = buffer.limit();
    buffer.limit(buffer.position() + 2);
    buf.put(buffer);
    buf.putInt(random.nextInt());
    buffer.limit(limit);
    buf.put(buffer);
    buf.flip();

    byte[] maskkey = new byte[4];
    buf.position(buf.position() + 2);
    buf.get(maskkey, 0, 4);
    int m = 0;
    while (buf.hasRemaining()) {
      int position = buf.position();
      buf.put((byte) (buf.get(position) ^ maskkey[m++ % 4]));
    }
    buf.flip();
    chain.nextUpstreamHandler(ws, buf, frame);
  }
}
